Tubular Bone Alterations in Familial Short Stature - GGH Journal

Tubular Bone Alterations of the FSS children (73%) than in phalangeal pattern profiles of
in Familial Short Stature: the unrelated adults with normal these two. groups were simila~.
stature (27%, P < 0.001 ). Also, the The ratIos between the fifth
Two Reports prevalence of rhizomelia was metacarpal and the other meta-
Familial short stature (FSS) ac- higher in the short parents of the carpal bones in the children with
counts for about 50% of the chil- FSS children (33%) than in the un- brachymetacarpia V showed that
dren who are seen by pediatric related adults with normal stature the fifth metacarpal bone was
endocrinologists for assessment (12%, P < 0.05). short in relation to the third and
of growth. These children usually Disproportionate shortening of fourth metacarpal bones, while the
are in good health, have no obvi- the lower limbs was more preva- opposite was true in the group
ous dysmorphology, and grow at a lent in the FSS children (32%) than without clinical brachymetacarpia
consistently normal rate. Growth in the healthy adolescents (11%, V. Moreover, it was also observed
usually proceeds parallel to the 5th P < 0.001). Disproportionate short- that there is a significant positive
percentile, and the predicted adult ening of the arms was more preva- correlation between height reducheight
is within range for the child's lent in the FSS children (35%) than tion and metacarpal and proximal
family. Essentially, these patients in children with normal stature phalangeal bone shortening in the
are short because their parents (10%, P < 0.01) and healthy ado- group with clinical brachyand
families are short. Since such lescents (8%, P < 0.001). metacarpia V. There was no
children are considered "normal," The presence of more than one correlation between height reductheir
skeletal anthropometric form of tubular bone alteration oc- tion and the length of the distal and
characteristics are presumed to curred more frequently in the chil- middle phalanges.
be similar to those in the rest of the dren and adults with FSS than in
"normal" population. the groups with normal height. Cervantes C, Lifshitz F. Human Bi-
In these two reports, however, a Most children and adults with FSS ology 1988;60:151-165. Cerhigh
prevalence of skeletal al- had one to four types of tubular vantes C, Lifshitz F, Levenbrown J.
terations in individuals with FSS bone alteration, while the majority Pediatr RadiQ/1988;18:248-253.
was noted. The occurrence of of individuals with normal stature
these characteristics has not been had either no tubular bone defect Editor's comment- The results of
reported previously in this patient or only one type of this defect. these two studies indicate a
group. In view of the high prevalence of very high prevalence of tubular
A detailed anthropometric study brachymetacarpia V in FSS pa- bone alterations, mainly disprowas
performed in 40 white children tients, the authors also performed portionate shortening of the limbs,
with FSS. Measurements were detailed radiologic anthropometry rhizomelia, brachymetacarpia lI:
compared with those from 40 chil- of the hand in 28 FSS children. and possible brachymetacarpia I,
dren of normal stature who were Lengths of each of the hand bones in children and adults with FSS.
matched for age, race, and sex, were measured and compared Since these characteristics are
and from 958 adolescent boys and with the normal standards devel- frequently seen in various syngirls
with normal stature. Anthro- oped by Garn and Poznanski. dromes characterized by skeletal
pometric measurements were also Moreover, the fifth metacarpal dysplasia, it seems reasonable to
obtained from 30 short parents of was compared with the other meta- speculate that children who fall in
FSS children and compared with carpal bones by obtaining ratios the lower end of the normal growth
those from 26 normal-statured and comparing these ratios with standards are short statured beparents
with FSS children and from the normal standards set by Garn. cause of an inherited abnormality
33 unrelated normal-statu red The results of this latter study in endochondral growth, the major
adults. revealed that most patients with process responsible for increase
Shortening of the fifth metacar- clinical brachymetacarpia V had in stature. The possibility of mild
pal bone was more prevalent in the radiologic evidence of fifth meta- hypochondroplasia in FSS pa-
40 FSS children (78%) than in the carpal bone shortening. The tients cannot be entirely ruled out,
children with normal stature (28%) metacarpal pattern profiles of the since this condition can present
and the healthy adolescents (39%, patients with and without brachy- with no stigmata other than short
P < 0.001). Rhizomelia was also metacarpia V differed. The short- limbed FSS and brachydactyly.
more prevalent in all FSS children est metacarpal bones in chil- There are isolated reports of fami-
(42%) than in the children with dren with clinical brachymetacar- lies with dominantly inherited
normal stature (15%, P< 0.01) and pia V were the first and fifth, while brachymetacarpia and short statthe
healthy adolescents (17%, in the children without clinical ure but no other associated ab-
P< 0.001). Likewise, shortening of brachymetacarpia V, the shortest normalities. The presence of brachythe
fifth metacarpal bone was metacarpal bone was the fourth, metacarpia V in the parents of
more prevalent in the short parents followed by the third and fifth. The continued on page 14
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continued from page 13 termining stature by expressing it-
affected FSS chi(dren suggests ~n self n~t only in over~/1 height but
heritance autosomal of dominant this characteristic. mode of In- also ening In of disproportionate tubular bones in short- those
This trait is also fairly common with FSS.
even in the normal population. The presence of tubular bone
Therefore its association with FSS alterations in an otherwise healthy
may be coincidental. However, patient with FSS should be caresince
these tubular bone al- fully evaluated before instituting
terations were significantly more therapy with growth hormone
in the FSS children and (GH). This is especially important
their parents and siblings than in since GH is now available in unlimthe
normal population, an inherited ited supply and pressure to treat
trait is most likely responsible for the short child with the drug is
pleiomorphic manifesta- again high. It may be reasonable
tions. Segregation analysis may to expect that children with FSS
help determine the mode of in- who also have skeletal abnormalof
these skeletal ities would respond less favorably
alterations. to GH or require a higher dose of
The findings in these two studies GH than would those with FSS and
the major role that endo- no bone abnormalities.
ossification plays in de- Fima Lifshitz, M.D.